Seal and insulate duct work or replace?


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Old 05-31-14, 03:03 PM
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Seal and insulate duct work or replace?

I am getting the ac and heating system in my home replaced. I got a few estimates and everyone recommended I replace my current duct work because of its age and lack of insulation. Unfortunately, I am not going to be able to pay for someone to do this so I will be attempting to tackle it on my own.

I visually inspected all the duct work and it looks very good to me. I didn't see any holes or major leaks but there was no insulation at all!! The house was built in 68 and it is metal duct that I believe to be original. I've read a bunch of stuff online and I am not sure if I would be better off sealing and insulating my current duct work or replacing it with the flex duct all the contractors have recommended to me.

There seem to be so many pros and cons for both and I am left very torn here. There isn't much space under the house and I am not a little person at all. I am trying to decide which option is best for me to continue exploring.

I went to HD and lowes to compare insulation types and the lack of selection surprised me. Lowes only sold flex duct, no insulation. HD only sold sleeves of insulation that looked to be for a new installation. So if I do decide to insulate instead of replace I may be ordering online.

I feel quite overwhelmed with all this currently. Any advice on how I should proceed next would be overly appreciated. Thanks in advance!
 
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Old 06-01-14, 07:58 AM
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Just because it is old doesn't mean it has to be replaced. Only reason to replace it is if you are increasing the size of the units. You will have to go to an HVAC supply house to find what you need. Sounds like the ducts are run in a crawl space?

Has your existing system been heating and cooling the house OK?
 
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Old 06-01-14, 09:22 AM
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It has been doing a decent job keeping the house warm and cool. The main reason I wanted to upgrade the ducts was to save some money on my heating and gas bill and also I was hoping more efficient ducts would put less of a strain on the system and help prolong its life.

The ducts are under the house. I found a local hvac store that I can check out monday for insulation. My main reason for visiting hd and lowes was to see what products were available for me to compare.

After reading A LOT more online, I am thinking that this how to page is the method I'll be following.

This is my first time doing any type of job like this so please let me know if I am missing something major! Once again, thanks for taking teh time to read over my post.

Save Money by Insulating Crawl Space Ducts: The Family Handyman
 
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Old 06-01-14, 10:00 AM
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I checked that link and the first word they used is "leaky". Unfortunately their solution seems to be wrapping the insulation around the ducts. The first step is to seal all seams with mastic or at least the foil duct tape. After they are 100% sealed, then you add the insulation.

However, you mention the ducts are below the house, is that a crawl space or basement? A crawl space will often be associated with moisture and ventilation concerns. Here is a related link discussing crawl space options.
BSI-009: New Light In Crawlspaces — Building Science Information

Bud
 
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Old 06-02-14, 10:23 AM
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I took a look at your how to page. I think after you work with that fiberglass for 10 min., you'll be cussing The Family Handyman.
 
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Old 06-02-14, 09:18 PM
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Bud- Thank you for pointing that out. I didn't mention in my first post, but I am going to go and clean off the ducts around the seams and reseal them with foil tape before I add the insulation. I don't think I have any major leaks currently but I will be rechecking for those as well. That was a big step for me to forget to mention!

It is a crawl space. To be honest, I have never thought of converting the crawl space into a basement like space like the link you posted talked about. Looks like I have yet another thing to add to my seemingly never ending to do list... I am definitely going to have to reread that page a few more times, some of the science it went into went right over my head.

I am going to be doing another inspection and the cleaning and sealing of the ducts tomorrow morning. I still have not been able to find duct insulation to use locally yet. I found an actual HVAC stores so hopefully they will have a better selection for me to choose from.
 
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Old 06-03-14, 05:06 AM
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There are several benefits to creating a conditioned crawl space.
1. You no longer need to insulate or even seal those ducts since that space now becomes part of the living space.
2. More than half of the air you breathe in a home comes from the crawl space through leaks between the house rim and foundation and even through the soil.
3. By insulating the crawl space and adding a vapor barrier, along with air sealing and possible a passive radon vent, that space can benefit from some of the conditioned air (supply and return) and the entire floor will warmer in the winter. It will also reduce heating and ac costs.

I know this is a long ways from what you were thinking, but newer energy efficient homes are being built this way to keep the ducts inside the conditioned space and reduce energy costs.

Bud
 
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Old 06-03-14, 05:57 AM
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Seal the Duct's

I have seen a product called Aeroseal, That product will seal from the inside of the duct. It will seal up a 5/8 inch hole in the duct. google the name im sure you can find a dealer near you.
Good luck
 
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Old 06-05-14, 10:22 AM
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I just wanted to thank everyone for their comments and advice. I finished cleaning and sealing the ducts in the crawl space yesterday. I cleaned them first and then applied foil tape at the seams. I turned the fan on before hand and could feel air coming fro the ducts so I KNOW this made a difference! Had y new good man 2.5 ton split system installed today so I am posting this message in comfort!

I will be looking more into turning the crawl space into a basement soon, thanks again for that tip bud. I had never thought of anything like that.
 
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Old 06-05-14, 11:33 AM
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Once you realize the amount of crawlspace air the family is breathing it hits home. Consider the crawlspace as just another part of your duct system and you want it to be as clean down there as those ducts you just cleaned.

Doesn't DIY add a nice touch of personal satisfaction?
Enjoy

Bud
 
 

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